Study on the fluorescence properties of lignocellulosic prehydrolysis liquor

The fluorescence properties were first probed for wood prehydrolysis liquor (PHL) in the present study. Besides fluorescence concentration quenching and pH effects, the excitation wavelength-dependent photoluminescence properties were also observed at excitation from 360 to 430 nm. In order to explore the inducement of visible fluorescence, the fluorescence analysis was performed for acid-soluble lignin; X-ray diffraction and Raman spectroscopy were performed for the PHL solids and revealed that graphitic carbon in the form of carbon nanodots (CNDs) exists in lignocellulosic PHL. Transmission electron microscopy and atomic force microscopic analyses further characterized the morphology of the graphitic carbon. These CNDs have an average diameter of 5.04 ± 0.89 nm and two forms of lattice spacing of 0.23 nm and 0.34 nm; the average height is 1.73 ± 0.71 nm. The discovery of the fluorescence and CNDs in lignocellulosic PHL will greatly widen its promising applications.